1. Field of the invention
The present invention concerns a control device for a feedback system such as an amplifier or a servomechanism.
2. Description of the Prior Art
Devices of this kind comprising at least one feedback loop suffer from stability defects due to phase differences introduced by the forward path and the feedback loop. This is the case with amplifiers incorporating an output transformer, for example, where oscillations can occur with a capacitive load, or with class D amplifiers whose switching mode operation entails filtering using inductors and capacitors. If the phase
shift at a specific frequency reaches 360.degree. the system oscillates. This limits the usable amount of feedback (which directly influences accuracy) and the bandwith. The system must meet particular known requirements and specifically the Nyquist criterion.
One aim of the invention is to provide a feedback system control device conferring high accuracy without compromising stability.